Train Heartnet, also known as "Black Cat," was an infamous assassin for a secret organization called Chronos...until he abandoned that cold-blooded existence to live on his own terms as an easygoing bounty hunter. But is Train's past as far behind him as he thinks?

I've only managed to read the first 3 volumes (couldn't bring my heart to read more >.<). What can I say, typical fightung-adventure manga with a horrible design of a gun. The protagonist is so typical, the food-loving happy-go-lucky who had this "scary eyes" when he gets angry. There's also a few scenes and characters that are copied from toher manga such as Hunter X Hunter (if you look carefully, you can see the resemblance).